Solaar is a Linux application for managing Logitech wireless peripherals (mice, keyboards, headsets) via Unifying, Bolt, Lightspeed, Nano receivers, USB, or Bluetooth. It provides device pairing/unpairing, battery monitoring, LED/RGB control (including per-key), button remapping, profile management, and rule-based automation for device events. The architecture consists of a core device communication library (logitech_receiver), GTK-based GUI, CLI interface, system tray integration, and DBus support for system events. Settings are persisted in YAML files, and the application maintains device state across reconnections via a persister mechanism. The codebase demonstrates solid engineering practices with modular separation of concerns, internationalization support, and comprehensive test coverage.